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The Anatomy of Curiosity: Inside NASA's Mars Rover

The Mars Science Laboratory and its Curiosity rover landed on Mars on August 5, 2012, following the infamous "seven minutes of terror" sky crane landing.

Mar 13, 2012

NASA/JPL

After a launch on Nov. 26, 2011, that NASA calls "among the most accurate interplanetary injections ever," the Mars Science Laboratory (MSL) is on its way to the Red Planet. If all continues to go well on its 254-day journey, MSL, carrying the Curiosity rover, will reach Mars in August. Curiosity's predecessors, Spirit and Opportunity, found evidence of past water on Mars, and in 2008 the Phoenix Mars Lander discovered perchlorate—a potential food source for microbes. Curiosity will pick up the hunt for signs of habitability by searching for organic material. "If you have sources of food and water and organic material, you could say you have the building blocks of life," says MSL co-investigator Nilton Renno. Mars missions are notoriously complex, so simply reaching the Red Planet will be an important milestone: The Russian Federal Space Agency's Phobos-Grunt spacecraft became stranded in low-earth orbit shortly after its launch in early November. Sixty-five percent of all previous Mars missions—including all 19 launched by Russia or the former Soviet Union—have failed to meet their goals. Here's how NASA built MSL for success.

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Anatomy of a Rover

Spencer Lowell

Curiosity tips the scales at nearly a ton and is almost 10 feet long. ­Previous twin rovers Spirit and Opportunity were 374 pounds each and just over 5 feet long. All three dwarf the first mobile Mars explorer, Sojourner; it was only 23 pounds and 2 feet long. (Above is a full-scale model of Curiosity at NASA's Jet Propulsion Laboratory on Oct. 28, 2011.)

The Power Source

Engineers hope Curiosity will rove for at least two years, relying on a unique power source. NASA has outfitted the vehicle with a nuclear-powered battery called a Multi-Mission Radioisotope Thermoelectric Generator (RTG). Drawing energy from the natural decay of plutonium-238 dioxide, an RTG produces almost three times the power of the solar panels that ran Spirit and Opportunity. And, unlike panels, RTGs perform well in dusty and dark conditions.

The SAM

Curiosity carries a 10-instrument package of tools and sensors—including the Sample Analysis at Mars (SAM) suite—to search for signs of life. One instrument features a remote-sensing device capable of targeting pinhead areas on rock formations from up to 23 feet away. ChemCam, as it is known, can then shoot a laser beam at the rock and analyze the vaporized material using light-reading spectrographs. "It has the potential to really study chemical evolution at a different scale than before," says co-investigator Diana Blaney. "We'll be able to map [material] composition at a fine scale." The SAM suite includes a quadrupole mass spectrometer and a gas chromatograph, which, along with the other devices, will work to analyze samples on the surface, inside Martian boulders, and belowground, in the quest to find organic matter.

Wheels and Actuators

At 20 inches in diameter, Curiosity's wheels are larger than those of an average car—and twice the size of the sometimes balky wheels on the Spirit and Opportunity rovers. Each wheel features high-traction cleats and a dedicated motor. The front and rear wheels actually have two motors apiece, enabling independent steering. Impressively agile, Curiosity can turn 360 degrees in place.

The Landing System

Unlike its smaller roving cousins, which used airbags to cushion their touchdowns, MSL is far too large and heavy (nearly a ton) to land safely by bouncing. Engineers devised a unique, highly complex (thus, nervous-making for NASA watchers) system called sky crane, essentially a rocket-powered backpack. In the initial stages of descent, a parachute 165 feet in diameter deploys. The parachute jettisons, and retrorockets kick in, providing upward thrust to further slow the rover's descent. Radar detects the landing surface and orients the crane upright. Hovering with the aid of the rocket streams, the crane lowers the rover to the surface on cables, then releases Curiosity to begin its ambitious mission.

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